The present invention relates generally to compensator design methodology and, more particularly, to a method for minimization of compensator design efforts by efficient utilization of sub-compensators.
The design and manufacture of new products has become an increasingly complex activity due to reliance on features requiring high performance compensators. It should be noted that throughout this specification the term compensator is used to describe various types of compensators for example in the communications arena a compensator may be an equalizer or in the control arena a compensator may be a feedback controller. Thus, to avoid confusion the term compensator is used throughout this specification.
In order to design compensators for a dynamic system, a designer must go through a number of operations in a design cycle. First, a desired performance of the dynamic system is identified and qualified. Then, the designer must create a model characterizing the system. In the process of constructing the model, the designer may rely on prior knowledge encompassing available scientific formulas and on experimental data gathered from previous experiments conducted on the system. The model obtained is a mathematical representation of the system""s behavior.
Next, using the model previously created, a compensator is designed for the system (design cycle). The compensator, that was designed, is tested to determine the performance of the compensated system. Depending upon the outcome of the tests, several portions of the design cycle may be repeated, until the design results in a final product (i.e., a compensator design) to be used with the system.
In the design cycle, standard design tools and methodologies are often used to design the compensator. These standard design tools and methodologies work well in situations where the compensator is being designed for a system that exhibits linear behavior. However, many systems and manufacturing processes exhibit nonlinear behavior or are made up of many similar but not identical systems. Thus, such systems have become too complex for standard tools and methodologies, and the compensator design performed by such methodologies is often inadequate.
Existing compensator design tools and methodologies are created for those skilled in the art of compensator design and require a high level of expertise. One shortcoming of such compensator design tools and methodologies is the selection of design parameters used in the design process. The design parameters must be selected manually by a knowledgeable designer, which often proves to be a difficult task. A typical example of such a tool is MATLAB(copyright) Control System Toolbox, available from Mathworks, Inc. of Natick, Mass.
Other known compensator design tools and methods attempt to solve the compensator design problem numerically by applying automatic optimization techniques to the entire set of design parameters in order to find optimal parameter values. For a large number of parameters, the optimization procedure is computationally intractable. One example of such software tool is QDES, described in detail in Linear Controller Design: Limits of Performance, by Boyd and Barratt, Prentice Hall 1991.
Other compensator design methodologies apply a weighted sum approach in order to size the model set and compensator set appropriately to arrive at a desired performance level. The weighted sum approach works well if all the variables are in the same units, but in most compensation problems the variables being taken into consideration are often unrelated and thus have a variety of units.
Thus, what is needed is a method and system for designing a compensator for a system where the system has particularly difficult behavior or where standard methods for compensator design are not good enough to compensate the particular behaviors of the system.
A method and system for designing a compensator is described. A structure of a model set and a compensator set is defined. The defined model set and compensator set is processed. Model set, compensator set, and model subsets are created from the processed model and compensator set. The created model set, compensator set, and model subsets are evaluated. The compensator design method provides adequate support for each model in the model set and results in attaining a high performance compensator that is adaptable in various environments.